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Description/Abstract

Background: Birth weight has been linked to increased morbidity and mortality in later life, but the mechanisms are poorly defined. It is not clear if adults with low and high birth weights have different percent body fat and pattern of fat distribution, which are associated with health outcomes, including cardiovascular disease. The purpose of this study is to assess if the percentage body fat and its distribution within the body differ between adults with a low and high birth weight, after adjusting for BMI. Methods: A total of 29 men aged 65-72 y old were recruited randomly from a Hertfordshire cohort with known birth weight and divided into two groups: a low birth weight group (<6.5 lbs); and a high birth weight group (>9 lbs). Body composition was assessed using DEXA Hologic Delphin and the results were processed using software v12.2, and expressed as mean +/-standard error. Results: Compared to the high birth weight group the low birth weight subjects were shorter (1.72 +/- 0.02 v 1.78 +/- 0.02m; P=0.05) and lighter (79.44 +/- 2.17 v 88.80 +/- 3.42 kg; P = 0.02). The low birth weight group also had a greater % body fat (28.71 +/- 1.03 v 25.53 +/- 1.85%; NS) despite a lower BMI (26.76 +/- 0.50 v 28.00 +/- 1.17 kg/m2; NS). When adjusted to the same BMI (27.31 kg/m2) using ANCOVA, there was about 5% more body fat (29.32 +/- 1.03 v 24.77+/-1.15 %; P=0.006) and more centrally located fat (ratio of non limb/ limb fat, 1.53 +/- 0.05 v 1.34 +/- 0.06; P=0.03). Conclusion: At the same BMI, older adults with a low birth weight had relatively more body fat and more centrally distributed fat than those with a high birth weight. This suggests that BMI should not be indiscriminately used to assess adiposity in low and high birth weight adults. The results could also help explain the higher risk of cardiovascular disease associated with poor fetal growth.